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><DIV
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><H1
><A
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></A
>Chapter 35. Extending <ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
></H1
><DIV
CLASS="TOC"
><DL
><DT
><B
>Table of Contents</B
></DT
><DT
>35.1. <A
HREF="extend-how.html"
>How Extensibility Works</A
></DT
><DT
>35.2. <A
HREF="extend-type-system.html"
>The <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
> Type System</A
></DT
><DD
><DL
><DT
>35.2.1. <A
HREF="extend-type-system.html#AEN49564"
>Base Types</A
></DT
><DT
>35.2.2. <A
HREF="extend-type-system.html#AEN49570"
>Composite Types</A
></DT
><DT
>35.2.3. <A
HREF="extend-type-system.html#AEN49577"
>Domains</A
></DT
><DT
>35.2.4. <A
HREF="extend-type-system.html#AEN49583"
>Pseudo-Types</A
></DT
><DT
>35.2.5. <A
HREF="extend-type-system.html#EXTEND-TYPES-POLYMORPHIC"
>Polymorphic Types</A
></DT
></DL
></DD
><DT
>35.3. <A
HREF="xfunc.html"
>User-defined Functions</A
></DT
><DT
>35.4. <A
HREF="xfunc-sql.html"
>Query Language (<ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
>) Functions</A
></DT
><DD
><DL
><DT
>35.4.1. <A
HREF="xfunc-sql.html#XFUNC-SQL-BASE-FUNCTIONS"
><ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> Functions on Base Types</A
></DT
><DT
>35.4.2. <A
HREF="xfunc-sql.html#XFUNC-SQL-COMPOSITE-FUNCTIONS"
><ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> Functions on Composite Types</A
></DT
><DT
>35.4.3. <A
HREF="xfunc-sql.html#XFUNC-NAMED-PARAMETERS"
><ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> Functions with Parameter Names</A
></DT
><DT
>35.4.4. <A
HREF="xfunc-sql.html#XFUNC-OUTPUT-PARAMETERS"
><ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> Functions with Output Parameters</A
></DT
><DT
>35.4.5. <A
HREF="xfunc-sql.html#XFUNC-SQL-VARIADIC-FUNCTIONS"
><ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> Functions with Variable Numbers of Arguments</A
></DT
><DT
>35.4.6. <A
HREF="xfunc-sql.html#XFUNC-SQL-PARAMETER-DEFAULTS"
><ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> Functions with Default Values for Arguments</A
></DT
><DT
>35.4.7. <A
HREF="xfunc-sql.html#XFUNC-SQL-TABLE-FUNCTIONS"
><ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> Functions as Table Sources</A
></DT
><DT
>35.4.8. <A
HREF="xfunc-sql.html#XFUNC-SQL-FUNCTIONS-RETURNING-SET"
><ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> Functions Returning Sets</A
></DT
><DT
>35.4.9. <A
HREF="xfunc-sql.html#XFUNC-SQL-FUNCTIONS-RETURNING-TABLE"
><ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> Functions Returning <TT
CLASS="LITERAL"
>TABLE</TT
></A
></DT
><DT
>35.4.10. <A
HREF="xfunc-sql.html#AEN49934"
>Polymorphic <ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> Functions</A
></DT
><DT
>35.4.11. <A
HREF="xfunc-sql.html#AEN49959"
><ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> Functions with Collations</A
></DT
></DL
></DD
><DT
>35.5. <A
HREF="xfunc-overload.html"
>Function Overloading</A
></DT
><DT
>35.6. <A
HREF="xfunc-volatility.html"
>Function Volatility Categories</A
></DT
><DT
>35.7. <A
HREF="xfunc-pl.html"
>Procedural Language Functions</A
></DT
><DT
>35.8. <A
HREF="xfunc-internal.html"
>Internal Functions</A
></DT
><DT
>35.9. <A
HREF="xfunc-c.html"
>C-Language Functions</A
></DT
><DD
><DL
><DT
>35.9.1. <A
HREF="xfunc-c.html#XFUNC-C-DYNLOAD"
>Dynamic Loading</A
></DT
><DT
>35.9.2. <A
HREF="xfunc-c.html#XFUNC-C-BASETYPE"
>Base Types in C-Language Functions</A
></DT
><DT
>35.9.3. <A
HREF="xfunc-c.html#AEN50472"
>Version 0 Calling Conventions</A
></DT
><DT
>35.9.4. <A
HREF="xfunc-c.html#AEN50499"
>Version 1 Calling Conventions</A
></DT
><DT
>35.9.5. <A
HREF="xfunc-c.html#AEN50557"
>Writing Code</A
></DT
><DT
>35.9.6. <A
HREF="xfunc-c.html#DFUNC"
>Compiling and Linking Dynamically-loaded Functions</A
></DT
><DT
>35.9.7. <A
HREF="xfunc-c.html#AEN50796"
>Composite-type Arguments</A
></DT
><DT
>35.9.8. <A
HREF="xfunc-c.html#AEN50820"
>Returning Rows (Composite Types)</A
></DT
><DT
>35.9.9. <A
HREF="xfunc-c.html#XFUNC-C-RETURN-SET"
>Returning Sets</A
></DT
><DT
>35.9.10. <A
HREF="xfunc-c.html#AEN50943"
>Polymorphic Arguments and Return Types</A
></DT
><DT
>35.9.11. <A
HREF="xfunc-c.html#AEN50973"
>Shared Memory and LWLocks</A
></DT
><DT
>35.9.12. <A
HREF="xfunc-c.html#EXTEND-CPP"
>Using C++ for Extensibility</A
></DT
></DL
></DD
><DT
>35.10. <A
HREF="xaggr.html"
>User-defined Aggregates</A
></DT
><DT
>35.11. <A
HREF="xtypes.html"
>User-defined Types</A
></DT
><DT
>35.12. <A
HREF="xoper.html"
>User-defined Operators</A
></DT
><DT
>35.13. <A
HREF="xoper-optimization.html"
>Operator Optimization Information</A
></DT
><DD
><DL
><DT
>35.13.1. <A
HREF="xoper-optimization.html#AEN51177"
><TT
CLASS="LITERAL"
>COMMUTATOR</TT
></A
></DT
><DT
>35.13.2. <A
HREF="xoper-optimization.html#AEN51212"
><TT
CLASS="LITERAL"
>NEGATOR</TT
></A
></DT
><DT
>35.13.3. <A
HREF="xoper-optimization.html#AEN51228"
><TT
CLASS="LITERAL"
>RESTRICT</TT
></A
></DT
><DT
>35.13.4. <A
HREF="xoper-optimization.html#AEN51278"
><TT
CLASS="LITERAL"
>JOIN</TT
></A
></DT
><DT
>35.13.5. <A
HREF="xoper-optimization.html#AEN51310"
><TT
CLASS="LITERAL"
>HASHES</TT
></A
></DT
><DT
>35.13.6. <A
HREF="xoper-optimization.html#AEN51332"
><TT
CLASS="LITERAL"
>MERGES</TT
></A
></DT
></DL
></DD
><DT
>35.14. <A
HREF="xindex.html"
>Interfacing Extensions To Indexes</A
></DT
><DD
><DL
><DT
>35.14.1. <A
HREF="xindex.html#XINDEX-OPCLASS"
>Index Methods and Operator Classes</A
></DT
><DT
>35.14.2. <A
HREF="xindex.html#XINDEX-STRATEGIES"
>Index Method Strategies</A
></DT
><DT
>35.14.3. <A
HREF="xindex.html#XINDEX-SUPPORT"
>Index Method Support Routines</A
></DT
><DT
>35.14.4. <A
HREF="xindex.html#XINDEX-EXAMPLE"
>An Example</A
></DT
><DT
>35.14.5. <A
HREF="xindex.html#XINDEX-OPFAMILY"
>Operator Classes and Operator Families</A
></DT
><DT
>35.14.6. <A
HREF="xindex.html#XINDEX-OPCLASS-DEPENDENCIES"
>System Dependencies on Operator Classes</A
></DT
><DT
>35.14.7. <A
HREF="xindex.html#XINDEX-ORDERING-OPS"
>Ordering Operators</A
></DT
><DT
>35.14.8. <A
HREF="xindex.html#XINDEX-OPCLASS-FEATURES"
>Special Features of Operator Classes</A
></DT
></DL
></DD
><DT
>35.15. <A
HREF="extend-extensions.html"
>Packaging Related Objects into an Extension</A
></DT
><DD
><DL
><DT
>35.15.1. <A
HREF="extend-extensions.html#AEN51807"
>Extension Files</A
></DT
><DT
>35.15.2. <A
HREF="extend-extensions.html#AEN51925"
>Extension Relocatability</A
></DT
><DT
>35.15.3. <A
HREF="extend-extensions.html#AEN51966"
>Extension Configuration Tables</A
></DT
><DT
>35.15.4. <A
HREF="extend-extensions.html#AEN51982"
>Extension Updates</A
></DT
><DT
>35.15.5. <A
HREF="extend-extensions.html#AEN52037"
>Extension Example</A
></DT
></DL
></DD
><DT
>35.16. <A
HREF="extend-pgxs.html"
>Extension Building Infrastructure</A
></DT
></DL
></DIV
><P
>   In  the  sections  that follow, we will discuss how you
   can extend the <SPAN
CLASS="PRODUCTNAME"
>PostgreSQL</SPAN
>
   <ACRONYM
CLASS="ACRONYM"
>SQL</ACRONYM
> query language by adding:

   <P
></P
></P><UL
COMPACT="COMPACT"
><LI
STYLE="list-style-type: disc"
><P
>      functions (starting in <A
HREF="xfunc.html"
>Section 35.3</A
>)
     </P
></LI
><LI
STYLE="list-style-type: disc"
><P
>      aggregates (starting in <A
HREF="xaggr.html"
>Section 35.10</A
>)
     </P
></LI
><LI
STYLE="list-style-type: disc"
><P
>      data types (starting in <A
HREF="xtypes.html"
>Section 35.11</A
>)
     </P
></LI
><LI
STYLE="list-style-type: disc"
><P
>      operators (starting in <A
HREF="xoper.html"
>Section 35.12</A
>)
     </P
></LI
><LI
STYLE="list-style-type: disc"
><P
>      operator classes for indexes (starting in <A
HREF="xindex.html"
>Section 35.14</A
>)
     </P
></LI
><LI
STYLE="list-style-type: disc"
><P
>      packages of related objects (starting in <A
HREF="extend-extensions.html"
>Section 35.15</A
>)
     </P
></LI
></UL
><P>
  </P
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